Collars to be worn by animals are well known and are worn for many different purposes.
For example, U.S. Pat. No. 5,857,434 discloses a collar worn by an animal for the detection of oestrus. The collar has a single housing for the required electronics and batteries attached to a woven strap, which hangs from the underside of the animal's (cow) neck and swings with the motion of the animal like a pendant. For certain sensors, this pendulant motion can prove problematic. In particular 3-axis accelerometers can produce erroneous outputs of the actual movement of the animal due to the swing motion of the housing. Further the antenna for wireless communication is accommodated in the housing at the underside of the animal which is not ideal for the antenna to achieve a clean line of sight with fixed antennae making the wireless communication unreliable. Furthermore, the woven strap is prone to wear and stretches over time such that the collar becomes loose, which can be hazardous to the animal as well as increasing the pendulum motion of the housing. Further, natural growth or changes in the animal's health and well being, as well as natural variation in the sizes between animals, cause changes in the size of the animal's neck and hence the size of collar required.
With increasing sensory and circuitry required for many animal monitoring systems, the housings have become increasingly heavy and as the animal will invariably rub it's neck against posts, feeding grills etc, the combination of the weight of the housing, loose straps and swing motion of the housing, the collar can cause severe abrasions and discomfort to the animal as well as severe damage to the sensory platform and circuitry and damage to collar.